Local Temperature and Humidity Impacts from Rain Garden Implementation in Contiguous U.S. Cities Using Urban Climate Modeling

As urban populations grow and built infrastructure ages, climate change impacts are increasingly pronounced in urban environments. Cities face more temperature and hydroclimatic extremes, increasing human livability concerns. Green stormwater infrastructure (GSI) installation is one possible adaptation tactic to combat effects of urbanization and climate change while increasing resilience and livability. However, GSI is not always a suitable solution everywhere due to prevailing weather patterns, soil type, and other factors, in addition to typically being designed primarily for a hydrologic purpose (e.g., runoff reduction). We utilize the Community Land Model Urban (CLMU) to simulate the temperature and humidity impacts from installation of rain gardens, a form of ground-based vegetated GSI, across urban areas in the contiguous United States. With a previously-developed rain garden parameterization within CLMU, we bridge microscale vegetation modeling and macroscale climate modeling. We completed two 10-year (2006-2015) simulations at a 10-km resolution: 1) a control run with CLMU defaults, and 2) a GSI run reflecting our implemented rain garden parameterization. Results demonstrate potential for GSI to provide air temperature cooling effects, while also quantifying the relationship between cooling and humidity changes due to enhanced evapotranspiration and impacts to human perceived comfort. This approach helps assess the possible co-benefits of local thermodynamic effects associated with vegetated GSI implementation throughout cities in different climates and regions.